Preheat oven to 250 F. Remove ham from bag, rinse and drain thoroughly. Place ham, cut side down, in a roasting pan. Using a paring knife score the fat of the ham from bottom to top, spiraling clockwise as you cut. Repeat process in a counterclockwise spiral.
Tent the ham with heavy duty foil, and cook for 3 to 4 hours or until the internal temperature at the deepest part of the meat registers 130 F.
Remove and use tongs to pull away the diamonds of skin and any sheets of fat that come off with them.
Raise the oven temperature to 350 F.
Brush entire ham with a liberal coat of mustard. Rub on brown sugar, packing loosely. Drizzle sugar lightly with bourbon, then pack on crushed ginger snaps.
Return to the oven, uncovered. Cook until interior temperature reaches 140 F, approximately 1 hour. Let ham rest for 1/2 hour before carving.